Sullivan adapted his style to use the faux-Rococo techniques he had developed in his play-illustrations in order to combine them with bizarre images of strange fantastical figures, drawing on the genre of the grotesque. Sullivan later also illustrated Carlyle's The French Revolution, though his work was far less varied than for Sartor Resartus. He used the same combination of Rococo and Grotesque to emphasise the violence erupting into the decorative world of Louis XVI and Marie Antoinette's court. Later books included The Rubaiyat of Omar Khayyam, using images of skeletons and animated pots.
One skeleton image was appropriated by Stanley Mouse and Alton Kelley for a Grateful Dead poster in 1966, and album cover in 1971: